The present invention relates to magnetic hard disk drives. More specifically, the present invention relates to a method of assembling micro-actuators.
In the art today, different methods are utilized to improve recording density of hard disk drives. FIG. 1 provides an illustration of a typical disk drive. The typical disk drive has a head gimbal assembly (HGA) configured to read from and write to a magnetic hard disk 101. The HGA and the magnetic hard disk 101 are mounted to the base 102 of a main board 103. The disk 101 is rotated relative to the base 102 by a spindle motor 104. The HGA typically includes an actuator arm 105 and a load beam 106. The HGA supports and positions a magnetic read/write slider 107 above the magnetic hard disk 101. The HGA is rotated relative to the base 102 along the axis of a bearing assembly 108 by a voice coil motor 109. A relay flexible printed circuit 110 connects a board unit 111 to the magnetic read/write slider 107.
FIGS. 2a-d provide an illustration of two embodiments of a piezoelectric micro-actuator. FIG. 2a illustrates a micro-actuator with a U-shaped ceramic frame configuration 201. The frame 201 may be Zirconia. The frame 201 may have two arms 202 opposite a base 203. A slider 204 may be held by the two arms 202 at the end opposite the base 203. A strip of piezoelectric material 205 may be attached to each arm 202. FIG. 2b illustrates the micro-actuator as attached to an actuator suspension 206. The micro-actuator may be coupled to a suspension tongue 207. Traces 208, coupled along the suspension 206, apply a voltage to the strips of piezoelectric material 205. These voltages may cause the strips 205 to contract and expand, moving the placement of the slider 204.
FIG. 2c illustrates an alternate version of the micro-actuator. In this embodiment, a metallic frame 209 has a base 210 with two arms 211 perpendicular to the plane of the base 210. A slider support 212 may hold the slider between the two arms 211. A strip of piezoelectric material 213 is coupled to each arm 211. The micro-actuator may then be attached to the head suspension 206 in the same manner as the ceramic micro-actuator, as shown in FIG. 2d. 
One embodiment of a method of manufacturing the metallic frame 209 is shown in FIGS. 3a-d. The frame 209 may be stainless steel, such as SUS304. As shown in FIG. 3a, the two arms 211 of the metallic frame 209 may be formed using vertical forming by machine or laser. A hole 301 may be formed on the slider support 212 to facilitate the slider 204 mounting. The support connections 302 and the base connections 303 may be narrowed to improve resonance. The two strips of piezoelectric material 213 may each have at least one contact pad 304 attached that allows the strips 213 to be electrically coupled to a control circuit. As shown in FIG. 3b, the strips 213 may be coupled to the arms 211 of the metallic frame 209. As shown in FIG. 3c, the slider 204 may be coupled to the slider support 212. The slider 204 may be coupled using epoxy or some other kind of adhesive. The epoxy may be cured using the hole 301 in the slider support 212. As shown in FIG. 3d, the micro-actuator may then be attached to the suspension tongue 207.
FIGS. 4a-b provides an illustration in a pair of charts of the effect of adhesive thickness on stroke and resonance. FIG. 4a compares the stroke in micrometers to the adhesive thickness in millimeters. In this example, stroke pertains to the amount of deflection of the slider caused by the micro-actuator. FIG. 4b compares the resonance frequency of the micro-actuator in kilohertz to the adhesive thickness in millimeters. Due to the small size of the micro-actuators and the fragile nature of the piezoelectric material, stress fractures and distortions remain problems.